An electronic circuit board includes electronic components to be mounted; a plurality of hard rigid board portions each of which has an insulating insulator and a conductive circuit pattern and electrically connects the mounted electronic component to the circuit pattern; and at least one soft flexible board portion which has an insulating insulator, has a conductive circuit pattern electrically connected to each of the circuit patterns of at least two rigid board portions among the plurality of rigid board portions, and is integrated with the rigid board portions which are electrically connected to the circuit pattern thereof. A plurality of contact relays as the electronic components is dispersedly arranged on the respective rigid board portions.